I just wanted to add 2 thoughts:
- Always wonderful to see thermodynamic equations in a post!
- The time-sensitive phenomena that @SaeranVasanthakumar described with the red and blue lines is exactly the reason why my example files of energy balances typically depict balances over an entire month. At any given timestep of the calculation, the energy into the building is rarely balanced with the energy out of the building (there’s a significant amount of energy being stored or released from the mass of the building). Even when you look at the balance over a whole day (which you can do in the example I linked to by plugging in “totaledDaily” results into the monthly bar chart), you will see that you get large storage terms for each day. So, if you are trying to do this validation, I recommend taking at least a month’s worth of simulation results with an epw that has 0 solar. And, even with that, don’t expect to get exactly the same U-Value that you have entered. Again, U-Value is a “miles per gallon” type of metric. While you can get close to it by “driving” (simulating) close to “highway” (NFRC) conditions, it’s very difficult to get an exact match without controlling every input of the simulation to mimic NFRC conditions.